Field of the Invention
The present invention relates to an information processing apparatus which determines whether interference occurs in grasping a workpiece.
Description of the Related Art
In recent years, there has been developed a technique for picking up an individual workpiece from a pile of workpieces, which uses a vision system to identify an individual workpiece from a pile of workpieces and recognize the three-dimensional position and orientation of the workpiece so as to grasp the workpiece with a hand that a robot has, for example, at a production line of a factory. In grasping the workpiece recognized by the technique, to prevent the hand from colliding with the container of the workpieces or with a peripheral object such as any workpiece other than the workpiece to be grasped, it is necessary to perform processing to determine in advance whether such a collision occurs.
For example, in a method discussed in Japanese Patent Application Laid-Open No. 2010-207989, a distance from a sensor attached above a target workpiece to the workpiece is obtained in an image format to recognize the position and orientation of the workpiece from the obtained distance information (range information), and then an interference determination is made in advance based on the shape, position, and orientation of a hand for grasping the workpiece and on the obtained distance information. More specifically, the hand is virtually moved upward to a reference height position in the z-direction of the recognized workpiece. Then, the hand is virtually lowered in the z-direction from the reference height position to a position for grasping the workpiece. After the hand is lowered, the first and second fingers are slightly opened at the grasping position and a virtual flat plate to be used for the interference determination is virtually set so as to have an appropriate allowance A from each of the finger tips of the fingers toward the lower part in the z-direction, and also to have an appropriate allowanceΔ between each of the finger tips and the workpiece. If, in the distance information in the image format obtained by the sensor, there is an object having a z-value larger than that of the virtual flat plate in a distance value of a pixel overlapping the virtual flat plate, it is determined that the interference will occur. This can determine at a high speed and in advance whether interference with an peripheral object will occur when the hand grasps the recognized workpiece.
However, in the method discussed in Japanese Patent Application Laid-Open No. 2010-207989, distance information representing the shape of the target workpiece to be grasped is also included in the obtained distance information in the image format. In the method discussed in Japanese Patent Application Laid-Open No. 2010-207989, each of the fingers is separated by an appropriate allowanceΔ from the workpiece to prevent an erroneous determination that there is interference with the target workpiece itself. For this reason, it may be determined that interference occurs with a peripheral object with which the hand does not actually interfere in grasping the target workpiece.